Heat Pipe Structure and Thermal Module Using Same

ABSTRACT

A thermal module includes a heat pipe structure, a plurality of heat radiation fins and a fan. The heat pipe structure includes a pipe having a first end, a second end and a middle section. The first and the second end are located adjacent to each other and form two heat-absorption sections, and the middle section forms a heat-dissipation section and is extended from the first end to the second end in a curve to have a substantially round shape defining a central opening. The heat radiation fins are arranged on the middle section of the pipe. The fan is correspondingly mounted to the heat-dissipation section and is faced to the heat radiation fins. With these arrangements, the thermal module is cost-effective and has largely upgraded heat transfer efficiency.

FIELD OF THE INVENTION

The present invention relates to a thermal module, and more particularly to a thermal module that includes a heat pipe structure, a plurality of heat radiation fins and a fan, and has the advantages of being cost-effective and having upgraded heat dissipation efficiency.

BACKGROUND OF THE INVENTION

Generally, a consumption electronic product internally includes a thermal module having a heat pipe. The heat produced by the internal electronic elements of the product during operation thereof is transferred by the heat pipe to a plurality of heat radiation fins of the thermal module. A fan of the thermal module draws external air toward the heat radiation fins, so that the heat transferred to the heat radiation fins is dissipated into ambient environment due to a thermal convection effect.

Currently, the arrangement of the heat pipe and the heat radiation fins of the thermal module in the consumption electronic device is frequently limited by the shape of the product, and the contact area between the heat pipe and the heat radiation fins is too small. One way to solve the above problem is to slantingly connect the heat radiation fins to one end of the heat pipe, so as to increase the heat transfer area between the heat pipe and the heat radiation fins. However, with the heat radiation fins slantingly connected to the heat pipe, the spacing distance between the heat radiation fins and the blades of the fan is not always same, which causes the flowing air to produce turbulence and accordingly make a relatively big noise to adversely affect the quality of the product. Further, the fan with the above problem also encounters the problem of high air resistance.

Generally, the heat pipe of the conventional thermal module is connected at the condensing zone at its tail end to the heat radiation fins, while the vaporizing zone at the head end of the heat pipe is extended to attach to or contact with a heat-producing element, such as a central processing unit (CPU) or a graphics processing unit (GPU). When the vaporizing zone absorbs the heat from the heat-producing element, the absorbed heat is further transferred to the condensing zone of the heat pipe. The heat transferred to the condensing zone is further transferred to the heat radiation fins connected thereto and is then finally dissipated from the heat radiation fins into ambient environment. While the above-structured thermal module can achieve the effect of heat dissipation, the overall heat dissipation effect is not good enough because the tail end of the heat pipe is the portion having the lowest heat transfer efficiency. As a factor inherent in the structure of the conventional heat pipe, the working fluid filled in the heat pipe tends to stagnate in the most rear portion of the heat pipe during the phase change between vapor and liquid, making the most rear portion of the heat pipe an inactive end in terms of heat dissipation. That is, the absorbed heat can not be transferred to the most rear portion of the heat pipe, or the condensed working fluid stagnates in the most rear portion without flowing back to the vaporizing zone or the head end, making the most rear portion an inactive end. Therefore, the tail end, or the condensing zone, of the heat pipe is practically not fully effective for transferring the heat to the heat radiation fins, resulting in lowered heat transfer efficiency and poor heat dissipation performance of the thermal module.

Moreover, in the case the heat pipe is non-horizontal in position with its tail end located at a lower place and the head end a higher place, the working fluid in the heat pipe will stagnate in the tail end and be drawn downward by the gravity to lose its ability of flowing back to the head end of the heat pipe, i.e. the vaporizing zone.

In brief, the prior art thermal module has the following disadvantages: (1) failing to reduce the air resistance and accordingly resulting in high operating noise of the fan thereof; (2) being cost-ineffective; and (3) tending to have an inactive end formed at the tail end of the heat pipe thereof, resulting in lowered heat transfer efficiency and heat dissipation effect.

It is therefore tried by the inventor to develop an improved heat pipe structure and a thermal module using same, so as to overcome the disadvantages in the prior art heat pipe structure and thermal module.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a heat pipe structure that does not have an inactive end to thereby have upgraded heat transfer efficiency.

Another object of the present invention is to provide a heat pipe structure that is cost-effective.

A further object of the present invention is to provide a thermal module that overcomes the problem of having an inactive end in a heat pipe structure thereof and can therefore have largely increased heat transfer efficiency.

A still further object of the present invention is to provide a thermal module that is cost-effective and has good heat dissipation effect.

A still further object of the present invention is to provide a thermal module that includes a heat pipe structure, a fan and a plurality of heat radiation fins, and the heat radiation fins can be arranged on the heat pipe structure to easily match the angular range of the fan's air-out side, so as to effectively achieve the lowest air resistance to increase the air flow volume of the fan while reducing the operating noise thereof.

To achieve the above and other objects, the heat pipe structure according to a preferred embodiment of the present invention includes a pipe having a first end, a second end and a middle section. The first and the second end are located adjacent to each other and form two heat-absorption sections for contacting with a heat source. The middle section forms a heat-dissipation section, and is extended from the first end to the second end in a curve to have a substantially round shape defining a central opening. With the above arrangements, the heat pipe structure of the present invention can effectively solve the problem of having an inactive end in the heat pipe, and can have increased heat transfer efficiency with reduced heat pipe cost.

To achieve the above and other objects, the thermal module according to an embodiment of the present invention includes a heat pipe structure, a plurality of heat radiation fins and a fan. The heat pipe structure includes a pipe having a first end, a second end and a middle section. The first and the second end are the head and the tail end of the pipe, respectively, and are located adjacent to each other. The first and the second end respectively form a heat-absorption section. The middle section forms a heat-dissipation section, and is extended from the first end to the second end in a curve to have a substantially round shape defining a central opening. The heat radiation fins are provided on the middle section of the pipe, and any two adjacent ones of the heat radiation fins together define a heat dissipation passage between them. The fan is correspondingly mounted to the heat-dissipation section, i.e. the middle section of the pipe, and has at least one air-in side and an air-out side. The air-out side is communicable with the heat dissipation passages. With the above arrangements, it is able to avoid the forming of an inactive end in the heat pipe structure. Therefore, the thermal module of the present invention can have upgraded heat transfer efficiency and is cost-effective, and the fan thereof can have effectively increased air flow volume and reduced operating noise.

To achieve the above and other objects, the thermal module according to another embodiment of the present invention includes a heat pipe structure, a plurality of heat radiation fins and a fan. The heat pipe structure includes a pipe having a first end, a second end and a middle section. The first and the second end are the head and the tail end of the pipe, respectively, and respectively form a heat-absorption section. The middle section forms a heat-dissipation section, and is extended from the first end to the second end in a curve to have a substantially round shape defining a central opening. Any two adjacent ones of the heat radiation fins together define a heat dissipation passage between them. The fan is correspondingly mounted to the middle section of the pipe, and has at least one air-in side, an air-out side, an upper cover and a heat-transfer lower cover. The heat-transfer lower cover has one side attached to the middle section. The heat-transfer lower cover and the upper cover together define a receiving space between them. The receiving space is communicable with the at least one air-in side and the air-out side, and is used to receive a fan wheel of the fan and the heat radiation fins that are located adjacent to the air-out side. The at least one air-in side is provided on a central portion of the upper cover and/or the heat-transfer lower cover; and the air-out side is provided on a periphery of the fan to face toward the heat dissipation passages. With the above arrangements, it is able to avoid the forming of an inactive end in the heat pipe structure. Therefore, the thermal module of the present invention can have upgraded heat transfer efficiency and is cost-effective, and the fan thereof can have effectively increased air flow volume and reduced operating noise.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

FIG. 1A is a perspective view of a heat pipe structure according to a first preferred embodiment of the present invention;

FIG. 1B is sectional view of FIG. 1A;

FIG. 1C shows a first variant of the first preferred embodiment of FIG. 1A;

FIG. 1D shows a second variant of first preferred embodiment of FIG. 1A;

FIG. 2A shows a first manner of using the heat pipe structure of the first preferred embodiment of the present invention;

FIG. 2B shows a second manner of using the heat pipe structure of the first preferred embodiment of the present invention;

FIG. 3A is an exploded perspective view of a heat pipe structure according to a second preferred embodiment of the present invention;

FIG. 3B is an assembled view of FIG. 3A;

FIG. 3C is an exploded perspective view showing a variant of the second preferred embodiment shown in FIGS. 3A and 3B;

FIG. 3D is an assembled view of FIG. 3C;

FIG. 4A is an exploded perspective view of a heat pipe structure according to a third preferred embodiment of the present invention;

FIG. 4B is an exploded perspective view of a first variant of the heat pipe structure according to the third preferred embodiment;

FIG. 5 is an assembled view of FIG. 4A;

FIG. 6A is a cutaway view of the heat pipe structure of FIG. 5;

FIG. 6B is a cutaway view of the first variant of the third preferred embodiment shown in FIG. 4B;

FIG. 7 is an assembled view of a second variant of the third preferred embodiment;

FIG. 8A shows a first manner of using the heat pipe structure of the third preferred embodiment of the present invention;

FIG. 8B shows a second manner of using the heat pipe structure of the third preferred embodiment of the present invention;

FIG. 9A is an exploded perspective view of a heat pipe structure according to a fourth preferred embodiment of the present invention;

FIG. 9B is an exploded perspective view of a variant of the heat pipe structure according to the fourth preferred embodiment of the present invention;

FIG. 10A is an assembled view of FIG. 9A;

FIG. 10B is an assembled view of FIG. 9B;

FIG. 11 shows a manner of using the heat pipe structure according to the fourth preferred embodiment of the present invention;

FIG. 12A is an exploded perspective view of a heat pipe structure according to a fifth preferred embodiment of the present invention;

FIG. 12B is an exploded perspective view of a variant of the heat pipe structure according to the fifth preferred embodiment of the present invention;

FIG. 13A is an assembled view of FIG. 12A;

FIG. 13B is an assembled view of FIG. 12B; and

FIG. 14 shows a manner of using the heat pipe structure according to the fifth preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.

Please refer to FIG. 1A that is an assembled perspective view of a heat pipe structure 1 according to a first preferred embodiment of the present invention, and to FIG. 1B that is a sectional view of FIG. 1A. As shown, in the first preferred embodiment, the heat pipe structure 1 includes a pipe 10. While the pipe 10 illustrated in the first preferred embodiment is a flat pipe and the heat pipe structure 1 is accordingly a flat heat pipe structure, it is understood that, in practical implementation of the present invention, the pipe 10 can be differently shaped according to an available internal arrangement space in an electronic device, such as a mobile electronic device, and a required heat transfer efficiency. For example, as shown in FIG. 1C, the pipe 10 is a substantially D-sectioned pipe and the heat pipe structure 1 is a D-shaped heat pipe structure; or as shown in FIG. 1D, the pipe 10 is a round-sectioned pipe and the heat pipe structure 1 is a round heat pipe structure.

The pipe 10 is internally filled with a working fluid (not shown), and has a first end 101, a second end 102, a middle section 104 and at least one wick structure 115. In the first preferred embodiment, the wick structure 115 is described as a sintered powder structure. However, the wick structure 115 for the present invention can be other types of structures, such as grooves, metal meshes, a metal coating or a porous structure, or any combination thereof. The wick structure 115 is formed on an inner wall surface of the pipe 10. The first end 101 can also be referred to as a first heat-absorption end, and is a head end of the pipe 10. The second end 102 can also be referred to as a second heat-absorption end, and is a tail end of the pipe 10. It is noted the second end 102 is located adjacent to the first end 101. In other words, the head end and the tail end of the pipe 10 are adjacent and parallel to each other. Meanwhile, the first and the second end 101, 102 both form a heat-absorption section 111, which can also be referred to as a heat-absorption zone. On the other hand, the middle section 104 forms a heat-dissipation section 112.

As shown in FIG. 2A, the heat-absorption sections 111 can be directly attached to a heat-producing element 4, such as a central processing unit (CPU), a graphics processing unit (GPU), or south/north bridge chipsets. Alternatively, as shown in FIG. 2B, the heat-absorption sections 111 can be attached to one side of a thermally conductive member 3, while the thermally conductive member 3 is attached at an opposite side to the heat-producing element 4. The thermally conductive member 3 absorbs heat from the heat-producing element 4 and transfers the absorbed heat to the heat-absorption sections 111. The thermally conductive member 3 includes a plurality of fixing arms 31, which are outward extended from two opposite lateral sides of the thermally conductive member 3. By extending a plurality of fastening elements (not shown) through holes provided on the fixing arms 31, the thermally conductive member 3 can be fixed to a substrate (not shown), on which the heat-producing element 4 is mounted, to attach to the heat-producing element 4.

With the first end 101 and the second end 102 of the pipe 10 being located adjacent and parallel to each other, the heat pipe structure 1 according to the present invention can continuously absorb heat and vaporize the working fluid, and accordingly, can overcome the problem in the conventional heat pipe design as having reduced heat transfer performance due to the existence of an inactive end at the condensing end. Therefore, with the design of the present invention, the heat pipe structure 1 can have effectively largely increased heat transfer efficiency and effectively upgraded gravity-resistant ability to ensure good heat dissipation efficiency. For example, when the pipe 10 is in a non-horizontal position with the first and second ends 101, 102 located at an upper position and the middle section 104, i.e. the heat-dissipation section 112, at a lower position, since the pipe 10 is a zero-inactive-end design with the two ends 101, 102 all being a heat-absorption section 111, the working fluid in the middle section 104 can effectively resist the gravity and quickly flow back to the first and the second end 101, 102 with the aid of the wick structure 115 provided on the inner wall surface of the pipe 10.

In addition, with the design of the present invention, the heat pipe structure 1 needs only one pipe to achieve the same heat dissipation performance that can only be achieved with two or more heat pipes in the prior art heat pipe structure. Therefore, the present invention also provides the advantage of being cost-effective.

Please refer to FIG. 2A. The middle section 104 forming the heat-dissipation section 112 is extended from the first end 101 to the second end 102 in a curve to form a substantially round shape. In other words, the first end 101, the second end 102 and the middle section 104 are integrally formed to provide a single heat pipe. The middle section 104 defines a substantially round central opening 113. Therefore, when the first and the second end 101, 102 absorb the heat produced by the heat-producing element 4, the absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112, i.e. to the middle section 104.

With the first and second ends 101, 102 being arranged adjacent and parallel to each other to form two heat-absorption sections 111 and with the middle section 104 being a substantially round section extended from the first end 101 to the second end 102, the heat pipe structure 1 has an overall structural design that does not have any inactive end to thereby enable effectively increased heat transfer efficiency. In addition, the heat pipe structure 1 of the present invention is cost-effective and has upgraded gravity-resistant ability to ensure good heat dissipation efficiency.

FIGS. 3A and 3B are exploded and assembled perspective views, respectively, of a heat pipe structure according to a second preferred embodiment of the present invention. Please refer to FIGS. 3A and 3B along with FIGS. 2A and 2B. The second preferred embodiment is generally structurally and functionally similar to the first preferred embodiment, except that, in the second preferred embodiment, a plurality of heat radiation fins 23 is provided to tightly attach to one side of the middle section 104 of the pipe 10. That is, the heat radiation fins 23 can be continuously arranged on along a partial or a whole surface of at least one side of the heat-dissipation section 112. Of course, the heat radiation fins 23 can be continuously arranged along one side of the middle section 104 within a range from 90° to 360°. In the illustrated second preferred embodiment, the heat radiation fins 23 are continuously provided on along one side of the middle section 104 by 360°. However, in practical implementation of the present invention, the area on the middle section 104 to be continuously covered by the heat radiation fins 23 can be adjusted according to the required heat dissipation effect. For example, in a variant of the second embodiment as shown in FIGS. 3C and 3D, the heat radiation fins 23 are continuously provided on along one side of the middle section 104 by 180°.

Any two adjacent heat radiation fins 23 together define a heat dissipation passage 231 between them for a fluid to flow therethrough. When the first and the second end 101, 102 absorb the heat produced by the heat-producing element 4, the absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112 formed by the middle section 104. The heat is then further transferred from the middle section 104 to the heat radiation fins 23 provided thereon. From the heat radiation fins 23, the heat is finally quickly diffused and dissipated into ambient air. Therefore, by providing a plurality of heat radiation fins 23 on along a whole side of the heat-dissipation section 112, the heat pipe structure 1 can have effectively increased heat dissipation area, allowing the absorbed heat to quickly dissipate from the heat radiation fins 23 into ambient air.

Please refer to FIGS. 4A and 5 that are exploded and assembled views, respectively, of a heat pipe structure according to a third preferred embodiment of the present invention. The third preferred embodiment is generally structurally and functionally similar to the first preferred embodiment, except that it is applied to form a thermal module 2. The thermal module 2 includes a heat pipe structure 1, a plurality of heat radiation fins 23, and a fan 21. The heat pipe structure 1 in the thermal module 2 according to the third preferred embodiment is the same as that in the first preferred embodiment, and is therefore not repeatedly discussed herein.

The heat dissipation fins 23 are provided on along one side of the middle section 104 of the pipe 10. In other words, the heat radiation fins 23 are continuously provided on along one side of the middle section 104 within a range from 90 to 360 degrees. In the illustrated third preferred embodiment, as shown in FIG. 5, the heat radiation fins 23 are continuously arranged on along one side of the middle section 104 by 360 degrees. However, in practical implementation of the present invention, the area on the middle section 104 to be continuously covered by the heat radiation fins 23 can be adjusted according to the required heat dissipation effect. For example, in a variant of the third embodiment as shown in FIG. 7, the heat radiation fins 23 are continuously provided on along one side of the middle section 104 by 180°. Therefore, by providing a plurality of heat radiation fins 23 on along a whole side of the heat-dissipation section 112, the thermal module 2 can have effectively increased heat dissipation area, allowing the absorbed heat to quickly dissipate from the heat radiation fins 23 into ambient air.

Any two adjacent heat radiation fins 23 together define a heat dissipation passage 231 between them for a fluid to flow therethrough. The fan 21 is a centrifugal fan, which is correspondingly mounted on one side of the middle section 104 of the pipe 10 and is located above the round central opening 113. The fan 21 has at least one air-in side 211, an air-out side 213, an upper cover 214 and a lower cover 215 opposite to the upper cover 214. The upper and the lower cover 214, 215 together define a receiving space 216 between them. The receiving space 216 is communicable with the at least one air-in side 211 and the air-out side 213, and is used to receive a fan wheel 217 of the fan 21 therein. In the illustrated third preferred embodiment, the upper cover 214 is welded to the heat radiation fins 23. However, in practical implementation of the present invention, the upper cover 214 can be otherwise screwed to or snapped onto the lower cover 215. The centrifugal fan in the third preferred embodiment can have two different configurations.

The first configuration of the centrifugal fan is shown in FIGS. 4A, 5 and 6A, and it includes one air-in side 211 and one air-out side 213. That is, the air-in side 211 is provided at a central portion of the upper cover 214; and the air-out side 213 is provided on a periphery of the fan 21 to communicate with the heat dissipation passages 231. The air-out side 213 has a size and a location corresponding to the span and the location of the heat radiation fins 23 on the middle section 104. For example, when the heat radiation fins 23 are continuously arranged on along one side of the middle section 104 within a range of 180 degrees, the air-out side 213 is provided on the periphery of the fan 21 corresponding to the heat radiation fins 23 and has a width of 180 degrees.

The second configuration of the centrifugal fan is shown in FIGS. 4B and 6B, and it includes two air-in sides 211 and one air-out side 213. One of the two air-in sides 211 is provided on a central portion of the upper cover 214 to communicate with the central opening 113, while the other on a central portion of the lower cover 215 to communicate with the receiving space 216 and the air-out side 213. The air-out side 213 is provided on a periphery of the fan 21 to communicate with the heat dissipation passages 231. The air-out side 213 has a size and a location corresponding to the span and the location of the heat radiation fins 23 on the middle section 104. For example, when the heat radiation fins 23 are continuously arranged on along one side of the middle section 104 within a range of 270 degrees, the air-out side 213 is provided on the periphery of the fan 21 corresponding to the heat radiation fins 23 and has a width of 270 degrees. Alternatively, when the heat radiation fins 23 are continuously arranged on along one side of the middle section 104 by 360 degrees, the air-out side 213 is provided on the periphery of the fan 21 corresponding to the heat radiation fins 23 and has a width of 360 degrees. The heat radiation fins 23 radially arranged on along one side of the middle section 104 by 360 degrees can most easily match the size and the location of the air-out side 213, and accordingly, can achieve the effect of having lowest air resistance and maximum air flow volume while largely increasing the overall heat dissipation efficiency and reducing the fan operating noise.

Please refer to FIG. 8A. When the heat-absorption sections 111 formed by the first and the second end 101, 102 absorb the heat produced by the heat-producing element 4, the absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112 formed by the middle section 104. The heat is then further transferred from the middle section 104 to the heat radiation fins 23 provided thereon. From the heat radiation fins 23, the heat is finally quickly diffused and dissipated into ambient air. Meanwhile, the fan wheel 217 of the fan 21 will guide external fluid through the at least one air-in side and pressurize the fluid. The pressurized fluid further flows through the air-out side 213 toward the heat radiation fins 23 and flows through the heat dissipation passages 231 to an outer side of the thermal module 2. In this manner, forced heat dissipation from the heat radiation fins 23 can be achieved to effectively increase the heat dissipation effect of the thermal module 2.

Alternatively, as shown in FIG. 8B, the heat-absorption sections 111 formed by the first and the second end 101, 102 absorb the heat produced by the heat-producing element 4 via a thermally conductive member 3, which is provided between the first and second ends 101, 102 and the heat-producing element 4. The absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112 formed by the middle section 104. The heat is then further transferred from the middle section 104 to the heat radiation fins 23 provided thereon. From the heat radiation fins 23, the heat is finally quickly diffused and dissipated into ambient air. Meanwhile, the fan wheel 217 of the fan 21 will guide external fluid through the at least one air-in side and pressurize the fluid. The pressurized fluid further flows through the air-out side 213 toward the heat radiation fins 23 and flows through the heat dissipation passages 231 to an outer side of the thermal module 2. In this manner, forced heat dissipation from the heat radiation fins 23 can be achieved to effectively increase the heat dissipation effect of the thermal module 2.

Please refer to FIGS. 9A and 10A that are exploded and assembled perspective views, respectively, of a heat pipe structure according to a fourth preferred embodiment of the present invention. The fourth preferred embodiment is generally structurally and functionally similar to the first preferred embodiment, except that it is applied to form a thermal module 5. The thermal module 5 includes a heat pipe structure 1, a plurality of heat radiation fins 53, and a fan 51. The heat pipe structure 1 in the thermal module 5 according to the fourth preferred embodiment is the same as that in the first preferred embodiment, and is therefore not repeatedly discussed herein.

Any two adjacent heat radiation fins 53 together define a heat dissipation passage 531 between them for a fluid to flow therethrough. The fan 51 is a centrifugal fan, which is correspondingly mounted to one side of the middle section 104 of the pipe 10 and is located below the central opening 113. The fan 51 includes at least one air-in side 511, an air-out side 513, an upper cover 514 and a heat-transfer lower cover 515 opposite to the upper cover 514. The heat-transfer lower cover 515 is made of a high thermal-conductivity material, such as a copper material. Further, the heat-transfer lower cover 515 is attached at its one side to a lower side of the middle section 104, and at its another side to an upper side of the heat radiation fins 53; and the heat radiation fins 53 is attached at their lower side to one side of the upper cover 514. The upper cover 514 and the heat-transfer lower cover 515 together define a receiving space 516 between them. The receiving space 516 is communicable with the at least one air-in side 511 and the air-out side 513, and is used to receive a fan wheel 517 of the fan 51 and the heat radiation fins 53 located adjacent to the air-out side 513. The centrifugal fan in the fourth preferred embodiment can have two different configurations.

The first configuration of the centrifugal fan is shown in FIGS. 9A and 10A, and it includes one air-in side 511 and one air-out side 513. That is, the air-in side 511 is provided at a central portion of the heat-transfer lower cover 515; and the air-out side 513 is provided on a periphery of the fan 51 to communicate with the heat dissipation passages 531. The air-out side 513 has a size and a location corresponding to the span and the location of the heat radiation fins 53. For example, when the heat radiation fins 53 in the receiving space 516 are continuously annularly arranged within a range of 270 degrees, the air-out side 513 is provided on the periphery of the fan 51 corresponding to the heat radiation fins 53 and has a width of 270 degrees. However, it is understood, in practical implementation of the present invention, the heat radiation fins 53 can be continuously annularly arranged adjacent to the air-out side 513 within a range from 90 to 360 degrees. Further, the only one air-in side 511 can be otherwise provided on a central portion of the upper cover 514 of the fan 51.

The second configuration of the centrifugal fan is shown in FIGS. 9B and 10B, and it includes two air-in sides 511 and one air-out side 513. One of the two air-in sides 511 is provided on a central portion of the upper cover 514 to communicate with the central opening 113, while the other on a central portion of the heat-transfer lower cover 515 to communicate with the receiving space 516 and the air-out side 513. The air-out side 513 is provided on a periphery of the fan 51 to communicate with the heat dissipation passages 531. The air-out side 513 has a size and a location corresponding to the span and the location of the heat radiation fins 53. For example, when the heat radiation fins 53 in the receiving space 516 are continuously annularly arranged adjacent to the air-out side 513 within a range of 180 degrees, the air-out side 513 is provided on the periphery of the fan 51 corresponding to the heat radiation fins 53 and has a width of 180 degrees. Alternatively, when the heat radiation fins 53 in the receiving space 516 are continuously annularly arranged adjacent to the air-out side 513 by 360 degrees, the air-out side 513 is provided on the periphery of the fan 51 corresponding to the heat radiation fins 53 and has a width of 360 degrees. The heat radiation fins 53 radially arranged in the receiving space 516 by 360 degrees can most easily match the size and the location of the air-out side 513, and accordingly, can achieve the effect of having lowest air resistance and maximum air flow volume while increasing the overall heat dissipation efficiency and reducing the operating noise. In addition, in practical implementation of the present invention, the heat radiation fins 53 in the receiving space 516 can be continuously annularly arranged adjacent to the air-out side 513 within a range from 90 to 360 degrees.

Please refer to FIG. 11. When the heat-absorption sections 111 formed by the first and the second end 101, 102 absorb the heat produced by the heat-producing element 4, the absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112 formed by the middle section 104. The heat is then further transferred from the middle section 104 to the heat-transfer lower cover 515 that has a relatively large heat dissipation area. From the heat-transfer lower cover 515, the heat is further transferred to the heat radiation fins 53. From the heat radiation fins 53, the heat is finally quickly diffused and dissipated into ambient air. Meanwhile, the fan wheel 517 of the fan 51 will guide external fluid through the at least one air-in side and pressurize the fluid. The pressurized fluid further flows through the air-out side 513 toward the heat radiation fins 53 and flows through the heat dissipation passages 531 to an outer side of the thermal module 5. In this manner, forced heat dissipation from the heat radiation fins 53 can be achieved to effectively increase the heat dissipation effect of the thermal module 5.

Please refer to FIGS. 12A and 13A that are exploded and assembled perspective views, respectively, of a heat pipe structure according to a fifth preferred embodiment of the present invention. The fifth preferred embodiment is generally structurally and functionally similar to the fourth preferred embodiment, except that, in the fifth preferred embodiment, the heat-transfer lower cover 515 has a designed size corresponding to a size of the pipe 10. That is, the heat-transfer lower cover 515 located below the middle section 104 is extended toward the first and the second end 101, 102, so that the first and second ends 101, 102 are attached to one side of the heat-transfer lower cover 515. In other words, in the fifth preferred embodiment, the heat-transfer lower cover 515 has a main portion located below the heat-dissipation section 112 formed by the middle section 104, and an extended portion located below and attached to the heat-absorption sections 111. In the illustrated fifth preferred embodiment, the heat-transfer lower cover 515 is substantially rectangular in shape and the upper cover 514 is substantially square in shape. However, the present invention is not limited thereto. In practical implementation of the present invention, the heat-transfer lower cover 515 and the upper cover 514 can be any other suitable shapes.

Please refer to FIG. 14. When the extended portion of the heat-transfer lower cover 515 is attached at another side to a heat-producing element 4, heat produced by the heat-producing element 4 is absorbed by the extended portion of the heat-transfer lower cover 515 and is then further transferred to the heat-absorption sections 111. Meanwhile, a part of the absorbed heat is directly transferred to the heat radiation fins 53 located below the main portion of the heat-transfer lower cover 515. In this manner, the heat transfer effect can be doubled. When the heat-absorption sections 111 absorb heat from the extended portion of the heat-transfer lower cover 515, the absorbed heat is quickly transferred from the heat-absorption sections 111 to the heat-dissipation section 112 formed by the middle section 104. Since the heat-transfer lower cover 515 has a relatively large heat transfer area, the heat transferred to the heat-dissipation section 112 can be quickly transferred to the heat radiation fins 53 via the large-area heat-transfer lower cover 515. From the heat radiation fins 53, the heat is finally quickly diffused and dissipated into ambient air. Meanwhile, the fan wheel 517 of the fan 51 will guide external fluid through the at least one air-in side 511 and pressurize the fluid. The pressurized fluid further flows through the air-out side 513 toward the heat radiation fins 53 and flows through the heat dissipation passages 531 to an outer side of the thermal module 5. In this manner, forced heat dissipation from the heat radiation fins 53 can be achieved to effectively increase the heat dissipation effect of the thermal module 5.

Please refer to FIGS. 12B and 13B that are exploded and assembled perspective views, respectively, of a variant of the fifth preferred embodiment. The variant of the fifth preferred embodiment is generally structurally similar to the preferred embodiment shown in FIGS. 9B and 10B, and is different from the fifth preferred embodiment in that the heat radiation fins 53 located in the receiving space 516 is continuously annularly arranged adjacent to the air-out side 513 within a range of 180 degrees, and the air-out side 513 is provided on along the periphery of the fan 51 within a range of 180 degrees corresponding to the heat radiation fins 53.

When the heat pipe structure 1 of the present invention is applied to form a thermal module, sine the heat pipe structure does not have any inactive end that has no heat transfer function, the thermal module with the heat pipe structure of the present invention is cost-effective and have upgraded heat transfer efficiency and gravity-resistant ability to ensure good heat dissipation efficiency. Further, the thermal module according to the present invention can also achieve the effect of lowest air resistance and reduced fan operating noise.

In practical application, the thermal module of the present invention can be used with a mobile device, such as a smartphone, a notebook computer, an iPad, a personal digital assistant (PDA) or an iPad2, or can be used with a display unit, such as a light-emitting diode (LED) display or a liquid-crystal display (LED display), so that the mobile device or the display unit can have the best heat dissipation effect and reduced operating noise.

In summary, the present invention is superior to the prior art heat pipe structure due to the following advantages: (1) it does not form any inactive end and thereby has largely upgraded heat transfer efficiency; (2) it is cost-effective; (3) it has upgrade gravity-resistant ability to ensure good heat dissipation effect; (4) the thermal module using the heat pipe structure of the present invention can have the lowest possible air resistance and reduced fan operating noise; and (5) it provides excellent heat dissipation effect.

The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims. 

What is claimed is:
 1. A heat pipe structure comprising a pipe having a first end, a second end and a middle section; the first end being located adjacent to the second end, and both of the first and the second end forming a heat-absorption section; the middle section forming a heat-dissipation section and being extended from the first end to the second end in a curve to form a substantially round shape and define a central opening.
 2. The heat pipe structure as claimed in claim 1, further comprising a plurality of heat radiation fins provided on the middle section of the pipe; the heat radiation fins being tightly attached to one side of the middle section, and any two adjacent ones of the heat radiation fins together defining a heat dissipation passage between them.
 3. The heat pipe structure as claimed in claim 2, wherein the heat radiation fins are continuously arranged on along one side of the middle section within a range from 90 to 360 degrees.
 4. The heat pipe structure as claimed in claim 3, wherein the heat-absorption section is directly attached to a heat-producing element.
 5. A thermal module, comprising: a heat pipe structure including a pipe having a first end, a second end and a middle section; the first end being located adjacent to the second end, and both of the first and the second end forming a heat-absorption section; the middle section forming a heat-dissipation section and being extended from the first end to the second end in a curve to form a substantially round shape and define a central opening; a plurality of heat radiation fins being provided on the middle section of the pipe, and any two adjacent ones of the heat radiation fins together defining a heat dissipation passage between them; and a fan being correspondingly mounted to the middle section of the pipe, and having at least one air-in side and an air-out side; and the air-out side being faced toward the heat dissipation passages.
 6. The thermal module as claimed in claim 5, wherein the fan is a centrifugal fan correspondingly mounted to one side of the middle section and is locate above the central opening defined by the middle section of the pipe; and wherein the fan has one air-in side provided on a central portion of an upper cover of the fan, and the air-out side is provided on a periphery of the fan to communicate with the heat dissipation passages.
 7. The thermal module as claimed in claim 5, wherein the fan is a centrifugal fan correspondingly mounted to one side of the middle section and is locate above the central opening defined by the middle section; and wherein the fan has two air-in sides, one of the air-in sides being provided on a central portion of an upper cover of the fan while the other on a central portion of a lower cover of the fan, and both of the two air-in sides being communicable with the central opening defined by the middle section of the pipe; and wherein the air-out side is provided on a periphery of the fan to communicate with the heat dissipation passages.
 8. The thermal module as claimed in claim 6, wherein the heat radiation fins are continuously arranged on along one side of the middle section of the pipe within a range from 90 to 360 degrees.
 9. The thermal module as claimed in claim 7, wherein the heat radiation fins are continuously arranged on along one side of the middle section of the pipe within a range from 90 to 360 degrees.
 10. The thermal module as claimed in claim 6, wherein the heat-absorption sections are tightly attached to one side of a thermally conductive member, and the thermally conductive member being attached at another opposite side to a heat-producing element.
 11. The thermal module as claimed in claim 7, wherein the heat-absorption sections are tightly attached to one side of a thermally conductive member, and the thermally conductive member being attached at another opposite side to a heat-producing element.
 12. The thermal module as claimed in claim 6, wherein the heat-absorption sections are tightly attached to a heat-producing element.
 13. The thermal module as claimed in claim 7, wherein the heat-absorption sections are tightly attached to a heat-producing element.
 14. A thermal module, comprising: a heat pipe structure including a pipe having a first end, a second end and a middle section; the first end being located adjacent to the second end, and both of the first and the second end forming a heat-absorption section; the middle section forming a heat-dissipation section and being extended from the first end to the second end in a curve to form a substantially round shape and define a central opening; a plurality of heat radiation fins, and any two adjacent ones of the heat radiation fins together defining a heat dissipation passage between them; and a fan being correspondingly mounted to the middle section of the pipe, and having at least one air-in side, an air-out side, an upper cover and a heat-transfer lower cover; the heat-transfer lower cover having one side attached to the middle section; the heat-transfer lower cover and the upper cover together defining a receiving space between them, and the receiving space being communicable with the at least one air-in side and the air-out side; the receiving space being used to receive a fan wheel of the fan and the heat radiation fins that are located adjacent to the air-out side; the at least one air-in side being selectively provided on a central portion of the upper cover or the heat-transfer lower cover; and the air-out side being provided on a periphery of the fan to face toward the heat dissipation passages.
 15. The thermal module as claimed in claim 14, wherein the heat-transfer lower cover is extended beyond the middle section toward the first and the second end of the pipe, and the first and the second end of the pipe being attached to one side of the heat-transfer lower cover.
 16. The thermal module as claimed in claim 15, wherein the fan is a centrifugal fan and has two air-in sides, one of the air-in sides being provided on a central portion of the upper cover of the fan while the other on a central portion of the heat-transfer lower cover of the fan, and both of the two air-in sides being communicable with the central opening defined by the middle section of the pipe.
 17. The thermal module as claimed in claim 14, wherein the heat radiation fins located in the receiving space are continuously arranged adjacent to the air-out side within a range from 90 to 360 degrees.
 18. The thermal module as claimed in claim 16, wherein the heat radiation fins located in the receiving space are continuously arranged adjacent to the air-out side within a range from 90 to 360 degrees.
 19. The thermal module as claimed in claim 14, wherein the heat-absorption sections are directly tightly attached to a heat-producing element.
 20. The thermal module as claimed in claim 16, wherein the heat-transfer lower cover has one side attached to the heat-absorption sections and another opposite side attached to a heat-producing element. 